Method of and means for extinguishing or smothering explosions in mines



Aug. 12 19240 H. KRUSKOPF METHOD OF AND MEANS FOR EXTINGUISHING 0R SMOTHERING EXPLOSIONS IN MINES Fiied April 30. 1921 fNVENTOR';

Patented Aug. 12, 1924.

UNMED STATES PATENT OFFICE.

HERMANN. KRUSKOPF, F DORTMUND, GERMANY.

' METHOD OF AND MEANS FOR EXTINGUISHING OR SMOTHERING EXPLOSIONS IN MINES.

Application filed April 30, 1921. Serial No. 465,765.

9 To all whom itmay concern:

Be it lmown that I, HERMANN KRUsK'oPF,

a citizen of'the German Republic, and resi-v a.-Procoss of ewtz'ngmlshz'ng or smothering ewplosz'ons in drifts pf coal-mines.-

- It has been found by practical experiments that downsand of -fine grain is the best material for extinguishing explosions and improving the blastin effect when used gs-tamping material in c arge-holes to be red.

The results are not equally good 'if' fine downsand is used for extinguishing explosions in drifts of coal-mines. In carrying this rocess into practical effect, the incombusti le dust will be'used in tiltable or projecting devices as described in my prior pat:

ent applications. Spch dust is also spread upon the walls of dnfts by means of suitable devices.

An explosion produced in drifts causes :the incombustible dust to whirl around in a cloud of dust in which the flame of the explosion will be smothered.

Heavy explosions will be extinguished instantaneously by the use of fine downsand,

but light exploslons in nascent stage will not be smothered unless they are developed to heavy explosions, because they have no sulficient power to cause heavy grain of down-.-

sand, in spite of its fineness, to whirl around and maintain the same suspended in air.

A new improvement of the method of extinguishing or smothering explosions in drifts of coal-mines is as follows:

Naturally washed earths which are not baked together or petrified by heat or pressure, have a grain without any sharp edge and of great fineness. Such dust dried by 'moderate heat of about 100 C.,."may be crushed or divided to light or flaky dust without sharp edges in mills by, little expense of motive power and in a less expensive way than any other materia Experiments'proved that this kind of dust is capable of smothering even weak or light explosions. A convenient material is furnished for example by clay, argil, lemon, dried at about 100 C. and suitably ground.

b.'Proce-ss of entz'nguz'shiny 0'! smothering explosions a. coal-mines and improving the blasting efi'ect of shots by tampz'ng.

From Fig. 3' of. the accompanying draw-. ings it will be noted how a paper tube well filled with fine powdered dry downsand is placed as a tamping upon the explosive charge for the purpose of improving the blasting effect thereof and preventing com-.

bustible gases and coal-dust from being ignited. The drawing shows that the dust containing tube is of less diameter than the charge hole and inserted loosely into the latter leaving the charge.-

Recent experiments proved that at the moment the charge is'fired the cartridge filled with dust will be compressed'at theoutlet of the charge-hole, thus opposing a heavy resistance, whilst the hollow space between the charge and tamping willbe increased. The

explosion gases enter said hollow space before they produce their blasting efleot. It has been found as new that said hollow space will considerably influence the results of the blasting work. Heavy blasting explosive materials are appreciated in mining owing to their strong action. Heretofore the tamp a small free space between it and ing of charge-holes was formed in most cases of wet clay, suitably and directly placed upon the explosive charge without leaving any hollow space, whereupon said tamping is firmly rammed upon the charge by means of the ramming-bar. This method is considered as being particularly convenient, according to the principle of the den-' sity of charge, for a most practical utilization of the explosive'material. With this old method it has been found at the moment a shot is fired in all coal-layer, that a la!" e amount of the coal to'be blasted will crushedto dust by the charge adjacent that part of the charge-hole which contains the explosivecharge. 'There occurs only a slight action producingalpieo'es of coal, so that the explosiv materi will not be utilized in an economicalway.

method'according to my present in.

* vention produces quite difierentj and much better blasting resultsi Owing to the'said hollow space the pressure surface on which spoiled for crushing coal to dust; in the neighbourhood ofthe explosive charge; The

the explosion gases produce their pressure be considerably, increased. At the same time the pressure of the ex losion gases will be reduced to a certain extentin direct relation to the increase of the'pressure surface within the charge-hole. Furthermore the pressure willbe improved-byra more complete combustionof the explosive charge.

Practical experiments proved that the ex plosive material will be utilized in a more economical way." By themethod according to this invention coal will be broken into large pieces. It has been found that 20 to of explosive material may be saved according to particular circumstances- By fir.- ing shots according to the. old method this amount of explosive material was uselessly "perfect combustionof the explosive charge owing to the hollow spacemay be noted In the form of soft after-damps. Experiments proved that the improved blasting efiect dethe. charge and the tamping, anda certain pendson the. size of the hollow space between size of the grain of the dust used, as well as .on thecompact uniform filling of the tamping cartridge- Theseconditions may be most easily fulfilled by the use of a paper tube filled wi fine dust, said tube beinginserted longi udina-lly into the portion of the chargeshole left free by the charge, the

tube being preferably of less diameter than the charge-hole. Thecartridge will be mserted loosely without ramming. In contradistinction to the old pasty rammed tamp-" this method the remaining 5 acesat the.

outlet of the charge-hole may e filled up with a suitablepasty or' powdered tamping, the diameter of which is or may equal {510 1or less than the diameter of the charge- The new objects of my present invention are: n

1. To use light or flaky dust without sharp edged corners, obtained from naturally washed earth which is not petrified by heat or pressure, such earth being dried at low heat and ground to dust by suitable power, for the pur ose of extinguishing explosions in drifts-o coal-mines bythe whirlfill the free ing around of said. dust under the action of Fig. 3 shows the shot in a layer of coal ready to be fired and tamped according. to p my improved method. cd is the charge, ac is a paper tube filled with fine sand of tending over the entire length of the latter. There is a hollowspace formed by loosely inserting said paper tube. In desig nates conducting wires for the ignitionof. the explosive charge... Z indicates the lower.

cut of the coal to. be blast.

-Fig. 4, c-ai is the explosive charge with less diameter than the charge-hole andex;

the charge-hole; a-c is a tamping without paper tube formed of fine, or pastysweg a1 7 hollow space f-c is formed by leaving 1111- material; is. the. hollow space.

filled a portion'o'fthe charge-hole in an? suitable way for, instance by making 9. mar on theramming bar or the like. The tamp- 'ing will be inserted into thecharge-hole by means of suitable device's, .for instance. in the'eventof a pasty tamping by means of the ramming bar, in the event of a powdered tamping by means ofa-tubeconta1nin the game and emptied the char -ho e by lo into or by a r .through said tu I L Fig. 1 shows a firmly rammed clay or argil tamping according to the old method. The argil or clay tamlping H is placed directly, without a ho ow space, upon the explosive charge 0-d. It is customary to rtion of the charge-hole oni y to 1 3 with t e tamping.

Fig. 2'shows how at the moment of the firing the hollow. space H has been increased by the compression of the tamping.

The e losion gases entered the same before producing. their blasting efiect. After being compressed said tamping closes the charge-hole in a gas-tight way with great resistance to pressure owing to its great length. The pressure surface on which-the gases entering the hollow space produce their blasting effect, has also been increased in proportion to the increase of the hollow ace.

Fig. 5 shows a tamping in which the ho1-.

low space is formed by means of a suitably shaped distance body 6. a is the e losive charge. a is a tamping filling the l diameter of the charge-hole.

In Fig. 6, a isa cross section through the charge containing portion of the charge-hole, b and b are cross sectigns through difierent shapes of rectangular distance bodies. a c

moaeaa and e are cross'sections through tampings made of equal or less diameter respectively thanthe charge-hole.

Fig. 7 shows various forms of tampings with distance bodies numbered 8 to 12 respectively.

Said distance bodies are formed of incombustible materials.

A powdered tamping according to my invention may be easily filled into tubes. Besides the easy filling,-this has the advantage that the kind and amount of dust may be easily controlled. Misfired shots may be easily discharged by simply withdrawing the tubes filled with fine dust.

For certain reasons the paper tube may also be omitted, in which case dust will be suitably filled into the charge-hole without tube, a suitable hollow space being left between it and the charge as shown in Fig. 4 with a good blasting efi'ect as a result, provided that the grain of the dust and size of said hollow space will be adequately chosen according to experiments.

Having now fully described my said invention, what I claim and desire to secure by Letters Patent, is:

1. The herein described method of tamping explosive-charge holes, consisting in inserting in such hole, following the application of the charge, a self-contained charge of tam iing material having a norln'al diameter ess than that of the hole, said material being released under the force of the explosion to eventually completely close the tamped end of the hole.

serting in such hole, following the applicaof incombustible dust.

3. The herein described method of tamping explosive-charge holes, consisting in in-' sertin in such hole, following the application 0% the charge, a charge of incombustible dustarranged in frangible container havling a diameter less than that of the charge 4. A tamping for charge holes, comprising a frangible container of smaller diameter than (tihe charge hole filled with an incombustible ust.

5. The herein described method of tamping explosive-char e holes, consisting ininserting in such ho e follo'wingthe application of the charge, an independent spacing tion of the charge, a self-contained charge -member. adapted to have one end engage the charge, and a self-contained charge of tamping material having a normal diameter less than that of the hole inserted to engage the other end of the member, the member spacing the charge and tamping in a predeterm1ned relation and said material being released under the force of the explosion to eventually completely close the tamped end of the hole.

Inv testimony whereof I have hereunto set my hand in presence of two witnesses.-

HERMANN KRUSKOPF.

Witnesses:

L. KRUsKorr,

M. Prmrm. 

